One‐cycle decoupling control method of multi‐leg switching power amplifier for magnetic bearing system

Abstract

The traditional current control algorithm of the multi-leg switching power amplifier (SPA) is complicated since the control of different phase currents is intercoupling. To address this problem, a novel control strategy based on one-cycle control is proposed in this study, which can enforce the average current of each phase is equal to the reference in each control cycle. Since it sets the duty cycle of the neutral leg as a constant, this method presents significant advantages such as quick dynamic response, easy control and decoupling of the phase currents. Taking a five-phase six-leg SPA, e.g. the mathematic model of the system was built, the duty cycle of the neutral leg was analysed, the principle of the novel control strategy was introduced, and the detailed implemented process was presented. Thereby, a high-speed switched reluctance motor system using the magnetic bearing is constructed to test this method. Both the simulation and experimental results have demonstrated the simplicity and effectiveness of the proposed method.